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Lower Limb Neuro
Lower Limb Neuro

Lower Limb Peripheral Mononeuropathy

February 15th, 2021


Peripheral mononeuropathy is a type of peripheral neuropathy affecting a single peripheral nerve.
  • Causes of Peripheral Mononeuropathy

  • Compression (particularly carpal tunnel and ulnar tunnel) - prolonged pressure, hereditary neuropathy with liability to pressure palsies (HNPP)
  • Trauma - blunt trauma, penetrating injury (e.g. knife, gunshot, glass)
  • Nerve ischaemia - trauma, thromboembolism, diabetes, atherosclerosis, excessive tourniquet use
  • Radiation injury
  • Peripheral Nerves of the Lower Limb

  • NerveSensoryMotor
    SciaticNilKnee flexion
    Lateral CutaneousLateral thighNil
    Common PeronealLateral calf
    Dorsum of the foot
    Toe extension
    Posterior TibialPlantar aspect of the footPlantar flexion
    FemoralAnterior thigh
    Medial calf
    Hip flexion
    Knee extension

Sciatic Nerve Palsy

The sciatic nerve branches into the tibial nerve and the common peroneal nerve, and as such palsy of the sciatic nerve will affect both of these nerves
  • Signs of Sciatic Nerve Palsy

  • Sciatic nerve proper - weakness of knee extension
  • Common peroneal nerve - sensory loss over the lateral calf and dorsum of the foot; weakness of dorsiflexion, foot eversion and toe extension
  • Posterior tibial nerve - sensory loss over the plantar aspect of the foot; weakness of plantar flexion
  • Causes of Sciatic Nerve Palsy

  • Direct trauma
  • Stretch injury
  • Hip dislocation
  • Intramuscular injections incorrectly performed in the gluteal region
  • Total hip replacement

Lateral Cutaneous Nerve Palsy

Lateral cutaneous nerve palsy is also known as meralgia paraesthetica.
  • Signs of Lateral Cutaneous Nerve Palsy

  • Sensory loss over the lateral thigh
  • No motor manifestations
  • Causes of Lateral Cutaneous Nerve Palsy

  • Occurs due to entrapment of the lateral cutaneous nerve beneath the inguinal ligament.

  • Increased intra-abdominal pressure - obesity, pregnancy
  • Tight clothing - particularly belts and suspenders

Common Peroneal Nerve Palsy

  • Signs of Common Peroneal Nerve Palsy

  • Foot drop
  • Weakness of ankle dorsiflexion and foot eversion
  • Sensory loss over the dorsum of the foot and lateral shin
  • Causes of Common Peroneal Nerve Palsy

  • Trauma - tibial or fibular fracture, ligamentous injury, nerve injury during surgery
  • Compression - tight casts, positioning during surgery, prolonged bed rest

Posterior Tibial Nerve Palsy

  • Signs of Posterior Tibial Nerve Palsy

  • Weakness of ankle plantar flexion
  • Sensory loss over the plantar aspect of the foot
  • Positive tinel's sign over the nerve posterior to the medial malleolus
  • Causes of Posterior Tibial Nerve Palsy

  • Tarsal tunnel syndrome - entrapment within the tarsal tunnel posterior to the medial malleolus
  • Distal tibial fracture

Femoral Nerve Palsy

  • Signs of Femoral Nerve Palsy

  • Wasting of the quadriceps
  • Weakness of hip flexion and knee extension
  • Reduced / absent patellar reflexes
  • Reduced sensation over the anterior thigh and medial calf
  • Causes of Femoral Nerve Palsy

  • Hanging leg syndrome - prolonged hanging of a leg over an edge e.g. off a mattress
  • Total hip replacement
  • Stretch injury
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